Agashashok Treeline Snowfence White Spruce Needle Nutrients and Isotopes (2017-2024)

The Arctic is warming much faster than the rest of the globe and the warming is seasonally asymmetrical, with modest warming during the summer months and extreme warming during the winter months. In many regions of the Arctic, extreme winter warming is coupled with observed and projected increases in winter precipitation. The combination of extreme winter warming and increasing winter precipitation will lead to rapid winter soil warming, with wide ranging consequences for ecosystem function. Warmer winter soils are generally associated with greater overwinter microbial activity, enhanced breakdown of soil organic matter and a flush of nutrients that may be available for plant uptake following snowmelt. Our long-term research near the Arctic treeline in the western Brooks Range of Alaska has revealed the potential importance of deeper snowpacks and warmer winter soils for the productivity of treeline trees and their advance into the tundra. We installed a well-replicated snowfence experiment to advance understanding of the effects of asymmetric warming and increased winter precipitation on tree growth and treeline advance in the Arctic. Here, we present white spruce needle nitrogen concentration, nitrogen-15, and carbon-13 of control and snowfence trees at treelines near the Agashashok River in northwest Alaska.